Written picture descriptions distinguish variants of primary progressive aphasia

Background Few studies have examined written discourse in primary progressive aphasia (PPA), a clinical syndrome due to frontotemporal lobar degeneration (FTLD) or Alzheimer's disease (AD). Objective We aim to: (1) determine differences in written discourse in PPA variants and controls using three approaches for analyzing narratives, and (2) make recommendations regarding the clinical utility of these approaches. Methods Individuals with PPA and healthy controls wrote descriptions of the Boston Diagnostic Aphasia Examination Cookie Theft Picture (CTP). We hypothesized that written narratives would be characterized by: (1) fewer total words, lower percentages of CTP content units (CUs) and Core Lexicon Words, and lower communication efficiency in all PPA variants compared to controls; (2) fewer content words in semantic variant PPA (svPPA) than in logopenic variant PPA (lvPPA), nonfluent variant PPA (nfvPPA), and controls; and (3) fewer function words in nfvPPA than in lvPPA and controls. Results Participants with svPPA had significantly lower percentages of total CTP CUs, CTP noun and verb phrase CUs, and Core Lexicon Words than lvPPA. Overall content unit (CU) profile of lvPPA was more similar to controls than to the other two variants. Written narratives of participants with nfvPPA and svPPA had significantly lower percentages of particles, a class of function words, than lvPPA participants. Conclusions Part of speech analysis showed a deficit in function words in nfvPPA. Content unit analysis distinguished svPPA and lvPPA, and is easily incorporated into the clinical environment when spoken data are scarce or difficult to obtain because of speech production impairments.